1. Field
Embodiments relate to a light emitting device module.
2. Background
Group III-V compound semiconductors such as, for example, GaN and AlGaN are widely used for optoelectronics and electronics because of many advantages such as, for example, easily controllable wide band gap energy.
In particular, light emitting devices, such as light emitting diodes or laser diodes, which use group III-V or II-VI compound semiconductors, are capable of emitting visible and ultraviolet light of various colors such as red, green, and blue owing to development of device materials and thin film growth techniques. These light emitting devices are also capable of emitting white light with high luminous efficacy through use of phosphors or color combination and have several advantages of low power consumption, semi-permanent lifespan, fast response speed, safety, and environmental friendliness as compared to conventional light sources such as, for example, fluorescent lamps and incandescent lamps.
Accordingly, application sectors of the light emitting devices are expanded up to transmission modules of optical communication means, light emitting diode backlights to replace Cold Cathode Fluorescence Lamps (CCFLs) which serve as backlights of Liquid Crystal Display (LCD) apparatuses, white light emitting diode lighting apparatus to replace fluorescent lamps or incandescent lamps, vehicular headlamps, and traffic lights.
In a light emitting device, a light emitting structure, which includes a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer, is disposed on a substrate formed of, for example, sapphire and a first electrode and a second electrode are respectively disposed on the first conductive semiconductor layer and the second conductive semiconductor layer. The light emitting device emits light having energy determined by an intrinsic energy-band of a material constituting the active layer in which electrons introduced through the first conductive semiconductor layer and holes introduced through the second conductive semiconductor layer meet each other. Light emitted from the active layer may vary based on the composition of the material constituting the active layer, and may be blue light, ultraviolet (UV) or deep UV light, for example.
The light emitting device as described above may be mounted in a package form to, for example, a backlight unit or a lighting apparatus.
FIG. 1 is a view illustrating a conventional light emitting device module.
In the light emitting device module 100, a light emitting device 10 is disposed on the bottom of a cavity of a package body 110 and a molding part 160 including phosphors 162 is charged around the light emitting device 10. The molding part 160 may serve as a lens.
A first lead frame 121 and a second lead frame 122 may be arranged in the package body 110. The light emitting device 10 may be electrically connected to the first lead frame 121 and the second lead frame 122 via wires 140 and 145 respectively.
A reflective layer R may be formed on the surface of the package body 110 and serve to reflect light emitted from the light emitting device 10 upward.
The package body 110 may be connected to a circuit board 180 such as, for example, a Printed Circuit Board (PCB) to receive current required for driving of the light emitting device 10.
However, the conventional light emitting device module as described above has the following problems.
The wires and the lead frames are required to supply current to the light emitting device and these materials may cause a cost increase. Moreover, the wires may hinder the progress of light emitted from the light emitting device, deteriorating light extraction efficiency.
In addition, the reflective layer R as described above may be formed of a high reflectivity metal, thus being discolored. For example, polypthalamide (PPA) constituting the package body may be easily discolored by heat.